Changing the future of your kidneys: PKD and beyond
When was the last time you thought about your kidney? If you’re a healthy individual, maybe not so much. But this unassuming organ is vital—and kidney diseases, like polycystic kidney disease, can put people at serious risk of health complications.
On this episode of Health Matters, we’re talking with Dr. Fouad Chebib to sing the praises of the small but mighty kidney, learn how to maintain kidney health, and gain a deeper understanding of polycystic kidney disease, also known as PKD.
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Kristen Meinzer: This is “Health Matters,” a podcast from Mayo Clinic where we discuss the latest medical advice, news, and research to help you live a happier and healthier life. My name is Kristen Meinzer — I’m a writer and journalist. In this episode, we’re talking about kidneys.
Most people have two kidneys, each about the size of your fist. If you’re lucky, maybe you never give them much thought — but kidneys do a lot for you. That becomes extra apparent when someone has kidney disease. In this episode, we’re finally going to give that small-but-mighty organ its due — and learn more about kidney disease and its complications.
To cover all this, I’m joined by Dr. Fouad Chebib, a nephrologist — aka kidney doctor — at Mayo Clinic in Jacksonville, Florida. He specializes in treating polycystic kidney disease — also known as PKD — and is actively working to find new groundbreaking treatments. Dr. Fouad Chebib, welcome to the show.
Dr. Fouad Chebib: Thank you. Thanks for having me.
Kristen Meinzer: We are so excited to talk with you today about a topic that affects many, many people. Kidney health. But I just have to start with kind of a silly question. I love kidney beans. Do kidney beans actually look like the kidneys in my body?
Dr. Fouad Chebib: They actually do. Yeah.
Kristen Meinzer: Oh, excellent! Well, with that out of the way, let’s start off with the basics: what do our kidneys do for us?
Dr. Fouad Chebib: Kidneys are really great, hard working organs that most of the time we don’t notice what they’re doing until we lose the function. The kidneys filter the blood so many times during the day — almost like 5 liters of blood that gets filtered by the kidney, maybe 30, 40 times a day.
Kristen Meinzer: That’s something like 150 to 200 liters of liquid that they process in a day? Like that could almost fill a bathtub! Wow!
Dr. Fouad Chebib: Yes. Significantly working throughout the day nonstop. Only to produce like almost two liters of urine. That filtration process removes all the toxins from our body, regulates the electrolytes — the sodium, the potassium, calcium, phosphorus — to keep them in balance. This is very important because, for example, if our potassium in the blood goes above normal level, it can make the heart stop.
Kristen Meinzer: There’s an enormous responsibility that they have to carry on their little shoulders.
Dr. Fouad Chebib: Yes. The kidneys keep everything in check: the acid base that is very important for all the other cells in the body, and then water regulation. If we are thirsty, the kidney senses that and then makes us concentrate the urine, so we don’t die from dehydration.
One of the normal physiological functions of the kidney is to regulate all the water balance, the electrolytes, the blood pressure. Also it has some hormonal roles, like the regulation of red cell production. If the kidney function goes down, you might get anemia or low red cell blood count. It also regulates our bone health as well.
Kristen Meinzer: Yet we know that some people live with only one kidney. We can donate a kidney to somebody else. In that case, why do we have two kidneys?
Dr. Fouad Chebib: Without getting too philosophical and maybe religious, we are born with two kidneys and each of them work about 50 percent of the total function. If we are born with one kidney, or even if we lose a kidney before age two, the other kidney will completely gain back all the function that is needed.
It grows a little bit more in size, and it filters a little bit faster and more to compensate for the other kidney. But also, if we donate the kidney at an older age, that other kidney that we have left also picks up about 20 percent extra. We’ll end up with, like 70 percent of kidney function that we started with, and that’s plenty enough.
Kristen Meinzer: Now, you said you didn’t really want to get philosophical or religious in your explanation of why we have two kidneys. But I’m curious about that. What would be a less — let’s say, slightly less scientific — reasoning for us having two?
Dr. Fouad Chebib: Sure. I mean, One is because they are very important organs so it’s almost like we have a backup plan if something goes wrong. But also, God has created 2 kidneys to help us potentially donate a kidney for someone who needs it.
Kristen Meinzer: That’s a beautiful take on why we would have two kidneys. It allows us to be the most generous versions of ourselves that we could be.
Dr. Fouad Chebib: Yeah. I’ve thought a lot about this because I wouldn’t be here without someone who has made that leap of faith to my father who had polycystic kidney disease and was on dialysis for 3 years and without that gift of life that came to us as a family, I wouldn’t be a physician.
There’s so much ripple effect on many, many people in the community. Giving one kidney would not only save the person who’s going to receive it, but it’s going to affect probably 10 to 20 people around them.
Kristen Meinzer: Wow. Would you be willing to tell us a little bit more about your father?
Dr. Fouad Chebib: He realized he had kidney failure towards the last minute when he had a lot of symptoms. He was very active, working, and having his business and then around early to mid-forties, he started getting build up of the toxins of the kidney. He was very tired and doctors eventually said, “Well, you have kidney failure from polycystic kidney disease and you need to be on dialysis very soon.”
I was in high school at the time and that’s when I saw him go through the burden of dialysis three times a week, and then one day a person came to his business and said, we’re going to help you out. Let’s see if we can find someone that could be a match for you. Low and behold, he was actually the altruistic donor . Again, I don’t want to be too religious, but we think it was a miracle from God, basically.
Kristen Meinzer: Oh, what an incredible, incredible gift.
Dr. Fouad Chebib: Yeah. He did so well for 20 years. Every year was for his way of thinking as a bonus. Unfortunately, he passed away a few years ago from complications from PKD, but 20 years of beautiful, beautiful life, seeing his kids grow up, go to college, seeing his grandkids, and it’s really meaningful.
Kristen Meinzer: Wow, that’s incredible. That made you want to be a polycystic kidney disease doctor?
Dr. Fouad Chebib: Yes, seeing that journey made me so passionate about making sure others don’t go through that burden. I thought, “Well, the best way to do this is to become a physician scientist and figure a cure out.” All my plans back then, when I was in my late teens, was to come to Mayo Clinic, and become the PKD expert to be able to change the lives of PKD.
We’re making some good progress in the PKD space, but also through Mayo Clinic and our lab. Hopefully my dad is proud that he inspired such a good thing that hopefully will affect a lot of lives.
Kristen Meinzer: A few things your kidneys do… filter blood, remove toxins, regulate electrolytes, produce urine, regulate our water so we don’t get dehydrated, maintain our acid-base balance, regulate the production of certain hormones, regulate our red blood cell production, and regulate our bone health. Whew! That’s a lot for two smallish organs. If you have two kidneys, they share the load.
With each working at 50 percent function. If you were to lose or donate one, the remaining kidney would step up to help, adding an extra 20 percent to its load. As a result, that one kidney would be working at 70 percent, which is enough for most people.
There’s no clear scientific reason we have two kidneys. Maybe one day we’ll discover an evolutionary or biological reason. Or, maybe it’s so we can give the gift of life to someone who needs it.
Kristen Meinzer: As we’ve started to discuss, healthy kidney function is so important. How do we know that our kidneys are functioning as they should?
Dr. Fouad Chebib: Most of the time our patients don’t feel much. They might have high blood pressure, but sometimes no one looks at other things. They consider it, “Oh, it’s with aging” and they treat the blood pressure. Especially if there’s no family history of other kidney diseases.
Then usually we don’t get any symptoms or side effects from the kidney not functioning well, unless the kidney function goes so low, like to the teens, 20 percent, 30 percent. Then, when it goes below 15 percent, that’s more advanced. It’s a silent disease until the kidney function is so low, or until we get a routine blood test, and then we see that the serum creatinine.
That gives us how the kidneys are filtering, and if that number is abnormal, your primary doctor would look at this and say, “Okay, maybe we need to involve a kidney doctor to look at why your kidneys are not working so well.”
Kristen Meinzer: Once you cross that threshold of 15 percent or lower, into more severe kidney disease, what kind of symptoms might you see?
Dr. Fouad Chebib: In addition to the blood work being abnormal, you’re going to start feeling very tired, maybe low appetite, maybe some nausea, vomiting, maybe fogginess, a little confusion and not feeling sharp. Build up of fluid — maybe some fluids in the lungs and getting short of breath, or maybe fluids in the legs and feeling that swelling in the legs. Or very high blood pressure because of buildup of salt and water in the system or other blood tests like high potassium and low bicarbonate.
Kristen Meinzer: When my kidneys are functioning as they should, I just won’t even notice. Even when I am starting to be unwell, I might not notice until things get quite advanced.
Dr. Fouad Chebib: That’s the typical scenario.
Kristen Meinzer: What causes kidney disease or kidney failure?
Dr. Fouad Chebib: The most common kidney diseases come from diabetes. That makes almost a third of what causes kidneys to fail. Usually it takes years of diabetes, especially if it’s not controlled. If we don’t control our sugars and if we don’t get diagnosed with diabetes early on, that could put patients at risk of kidney disease.
Then also there’s high blood pressure, especially if it’s not controlled, that can cause the kidneys to fail. There’s a 3rd category called glomerulonephritis, which is inflammation of these filters. We have millions of these filters in each kidney that filter the blood many, many times during the day.
Any autoimmune diseases or inflammation or things like that can suddenly cause the kidneys to fail. Then fourthly, inherited kidney diseases like polycystic kidney disease.
Kristen Meinzer: Let’s talk more about polycystic kidney disease, or PKD, which we mentioned earlier when talking about your father. What is PKD?
Dr. Fouad Chebib: PKD is an inherited kidney disease. There’s two types. There’s the autosomal dominant and the autosomal recessive. They both cause kidney cysts, but the autosomal recessive is much more rare. It’s a childhood disease. Most of the time they’re diagnosed at birth and they have a lot of kidney and lung issues early on.
Now, we’re going to focus on the autosomal dominant polycystic kidney disease. That’s the AD PKD. That’s the more common type. Usually one parent has autosomal dominant prostate kidney disease and that puts each child at 50 percent risk of having the disease. If the child has ADPKD, they’re born with many kidney cysts, which are fluid-filled sacs, on each kidney.
There’s probably going to be hundreds of them. Early on in life, in childhood and teenage years, these kidney cysts are going to be very small. Most likely they won’t have any symptoms. Then later on, into early adulthood, these cysts are going to start filling with fluids.
There’s going to be tens and hundreds of these cysts on each kidney. The kidneys are going to start growing in size. Instead of the size of a fist, it’s going to become almost the size of an American football.
Kristen Meinzer: What happens when the kidneys are that big?
Dr. Fouad Chebib: That can start causing some symptoms like chronic pain, flank pain, pain in the back, or pain in the abdomen, whether from bleeding inside those cysts or cyst infection. Or sometimes, patients come in with lots of blood in their urine. They probably had some contact sports and one of these kidney cysts can burst and spill blood into the urine.
Kristen Meinzer: Is that how PKD gets diagnosed — you start getting symptoms?
Dr. Fouad Chebib: Sometimes they won’t have any symptoms, but then when they go to their primary doctor, they check their blood pressure and it’s high, and then they start looking into why they have high blood pressure at an earlier age. They do blood tests, they look at the family history, they do a kidney ultrasound, and they find these kidney cysts there.
That’s the usual way of diagnosing PKD. Either someone in the family has PKD and you want to know if you have it or not, then you go and get checked. Or you have some sort of symptoms, blood in the urine, kidney infection, kidney stone, high blood pressure, abnormal blood work, and then you get tested and get the diagnosis.
Dr. Fouad Chebib: If your kidneys are working well, you’ll probably never notice — everything just feels like your body is doing what it’s supposed to. When kidney function starts to decline, some of the early symptoms are high blood pressure and abnormal serum creatinine numbers on routine blood tests. These can progress into uremic symptoms like fatigue, low appetite, nausea, vomiting, brain fog, and fluid buildup in the body, eventually leading to kidney failure.
The most common causes of kidney failure are diabetes, high blood pressure, kidney filter inflammation, and polycystic kidney disease — something Dr. Chebib knows well. PKD is caused by cysts in the kidneys. Over time, these cysts fill with fluid and cause the kidneys to get larger, often resulting in kidney failure.
PKD sounds — and let’s face it, is — pretty scary. But there’s hope! With Dr. Chebib on the case, we could see some revolutionary new treatments for this disease. Let’s do a deep dive into how complex diseases like PKD are managed.
Kristen Meinzer: Is it possible to fully treat PKD?
Dr. Fouad Chebib: PKD is a lifelong multi-system disease, so it does affect mainly the kidneys and other organs that are affected by the kidneys. But these kidneys are going to fail at some point. Now, some patients, they might have a very mild form of polycystic kidney disease, and they might not end up having kidney failure, needing dialysis or transplant.
That’s a small minority, maybe 10, 15 percent of patients with PKD. Now, the majority would have kidney failure. We don’t have a way to completely stop it yet or reverse it, but we’re working on it.
But until then, we have ways to slow it down, which means instead of our patients reaching kidney failure in their forties, maybe fifties or sixties, we want to give them maybe an additional five or 10 years extra on their kidneys before they need dialysis or transplantation.
Kristen Meinzer: What are some of the ways you can slow down PKD?
Dr. Fouad Chebib: Everybody, even if we don’t think they’re going to reach kidney failure, they need to be at their healthiest. If they have excess weight, we want them to do some lifestyle modifications to lose that weight and maintain a healthy weight. It’s important to maintain a very healthy lifestyle. Second is we want to suppress that thirst hormone.
Now, when you have polycystic kidney disease, that thirst hormone is going to go to where the kidney cysts are and it’s going to stimulate them to keep growing and making more fluids. The Achilles heel of PKD is that thirst hormone. One way to reduce that thirst hormone in your system is by hydrating a lot with water throughout the day and even at night. We push our patients to drink quite a bit of fluids, like 3 liters, and keep track of their urine.
If it starts getting dark and concentrated, that means they’re losing fluids probably from sweating or exercise or other things. Then the next thing is, in addition to water, we need to cut down on the sodium or salt in our food, not only to suppress the thirst hormone easier with fluids, but also to control blood pressure.
Then we want to control blood pressure early on. We try to lower the blood pressure a little bit more aggressively. Also there’s studies that say if we control it, it could help slow down the disease process.
Kristen Meinzer: Lifestyle plays a big role. Are there medications that can help as well?
Dr. Fouad Chebib: There’s now one FDA approved treatment. The medication name is called Tolvaptan. The trade name is JYNARQUE in the United States. It’s an interesting medication. It’s a twice a day medication. It blocks the effect of the thirst hormone. Then the thirst hormone is not stimulating the kidneys anymore. It has been shown to reduce the growth of the kidneys. The kidneys grow year after year.
Let’s say if as a matter of natural history, they’re growing at 100 percent. Then with tolvaptan, they should be growing at 50 percent. Then, in terms of kidney function, a 30 percent reduction in the progression of the kidney function declines, meaning for every four years of treatment, we can push the date of dialysis or the need for transplant by one year.
The earlier we start, the better, because it adds up. There’s other medications that might come our way in the next few years. They’re being tested in clinical trials. We hope eventually in the next few years, we’re going to have more options.
We can do tolvaptan, but also maybe add another type of medication, and then pick and choose what’s the best for our patients. Then hopefully slow it down much more.
Kristen Meinzer: Now you mentioned PKD, it’s a genetic disease. Do people usually know if they’re at risk because of their family history?
Dr. Fouad Chebib: The diagnosis of polycystic kidney disease is typically clinical, but typically what we need is, does our patient have a family history of PKD or not? But there’s a 20 percent chance that they might not know about any other member in their family.
Or it could be that yeah their family members were not screened or tested correctly or they passed away from other things and they didn’t have that diagnosis. But if there is no family history, or if things don’t make a lot of sense where we have only a few kidney cysts, but the kidney function is quite low, we offer genetic testing.
Kristen Meinzer: Interesting. How does genetic testing work?
Dr. Fouad Chebib: Genetic testing would look at specific genes that can cause polycystic kidneys. They can just swab their cheek. We get the DNA from these cells and then we test it. Or we can get the blood test and then get the DNA from the white cells from the blood test. It’s still controversial.
Not everybody offers genetic testing, but now that we know more, it’s also easier to get it. In my practice, I offer it to all of our patients because I believe that the more information we have, the more we can understand the trajectory of the disease. Also we’re pushing the envelope a little bit so we have potential treatments that could be what we call genetic therapy.
They are coming into clinical trials and they’re specific to a particular subset of patients with, for example, PKD-1 mutation. We can go to those patients and say, you have potentially a treatment available to you. Do you want to join our clinical trial? Then hopefully if it’s approved and it shows effectiveness, then of course it’s going to become standard of care to check genetic testing.
Kristen Meinzer: What are these genetic treatments?
Dr. Fouad Chebib: PKD-1 is the gene. PKD-1 creates polycystin-1 protein. There’s a subset of mutations or these changes of the DNA. Depending on where the mutation is, it can affect the protein differently. Because of this mutation, they get stuck in the processing factory.
One genetic therapy helps them get back to where they should be going. That can hopefully help 10 percent of patients. But there’s other genetic therapies that are also clinical trials that can affect how the proteins are also processed, but in a way that we keep that machinery in the cell working a little bit harder, to make a little bit more of the normal protein and then hopefully slow the disease process.
A lot of great advancement. I mean, things that we wouldn’t imagine 10 years ago. We’re going to be the first disease to have these types of treatments too. Also it’s probably going to help other diseases in the process.
Kristen Meinzer: Oh, that’s fantastic. Imagining all these technologies. It almost sounds like sci-fi. Going to go in there, going to change how the actual machinery works. That’s incredible.
Dr. Fouad Chebib: It is.
Kristen Meinzer: Wow.
Dr. Fouad Chebib: We’re also trying to do many therapies for the kidneys and liver, either to rejuvenate these kidneys, but also to work on a way to keep these kidneys functional. I hope we are pushing the envelope at Mayo Clinic.
We think we’re getting closer and closer for gene therapies where, how I envision it is, we’re going to have someone diagnosed with PKD early on. We go and treat the kidney with gene therapy, and then that’s it. We fix PKD, and they don’t have to worry about kidney failure later on. That looks like science fiction right now, but I think we’re getting there.
Kristen Meinzer: Oh, I’m looking forward to that too. It sounds like there really is a lot of hope.
Dr. Fouad Chebib: Yes.
Kristen Meinzer: Now, you have worked with patients to help manage PKD with all of the current treatments and the current knowledge. How have you seen some of these treatments and approaches play out with your patients?
Dr. Fouad Chebib: We mentioned PKD, a lifelong disease. So we get to know them. We get to know their families, because a lot of the time they have kids and nephews, nieces, uncles, aunts, they all have PKD. Or, if they don’t have PKD, they’re so eager to donate the kidney to help them.
We get to know their stories and we follow them for so many years. One patient that really took care of themselves. They were diagnosed in their early forties, and they were the first in the family to have PKD. That was a long time ago. The patient got on Tolvaptan through the clinical trials and continues to be on it now.
They are around 60 years old. They’ve been on treatment for 20 years. Then I look at their kidney function and how it progressed. I saw how effective the treatment is. It’s a great example to show that if you put the brakes early on in the disease, one by getting the best treatment offered at the time, but also to take care of your blood pressure, stay healthy, not gain weight, no smoking, good hydration.
The more you invest in your health from lifestyle and treatment, the more it’s going to pay off later on. At age 40, it was anticipated they would already be on dialysis by age 60, but now they’re 20 years later, age 60 with excellent kidney function. That tells me all this work that the patient has put in does pay off, eventually.
Kristen Meinzer: That’s fantastic.
Dr. Fouad Chebib: Also a lot of patients that we meet, they don’t let the disease or PKD control their lives. They continue to be very optimistic. They exercise, they enjoy all the hobbies they need. They just say, “Okay, this is one chapter of my life. And then the next chapter, maybe it’s going to be a transplant,” but they see the glass half full, not the glass half empty.
Kristen Meinzer: I mean, whether it’s dealing with PKD or just our health in general, being able to not walk around in a state of hopelessness all the time, that’s not going to do us any good no matter what.
Dr. Fouad Chebib: Exactly. Absolutely.
Kristen Meinzer: Dr. Chebib, for all the folks out there who want more information on PKD, how to treat it, how to manage it, can you tell us where they can go?
Dr. Fouad Chebib: There’s a lot of resources online. There’s great resources on the Polycystic Kidney Disease Foundation website that we also support and I’m part of their board of directors. But also at Mayo Clinic, for every disease, we have great information. But specifically for polycystic kidney disease, we have created something called the Mayo Clinic PKD Resource Center.
In there, we’ve been diligently working for the past several months on creating articles about polycystic kidney disease. Going into a deep dive in each of the aspects of PKD, whether the kidney, the kidney function, lifestyle, PKD diet, blood pressure control, gene therapy, liver disease, intracranial aneurysm — so there’s many other organs that PKD affects.
Plus there’s some illustrations to make things easier to understand. But also, I’m very excited that we’ve done a series of short videos. They also explain PKD, and then also patients’ journeys, and how they dealt with PKD and how they see PKD in their own eyes and their stories. The final advice I would say, do not count on Dr. Google because each patient has their own journey.
Don’t assume the worst, even if you get a diagnosis of PKD, it might be very mild, and you’re not going to have to change your whole life because of PKD. Or if it’s a little bit more severe, there are ways to slow it down. Don’t assume the worst case scenario. Wait until you meet with your PKD doctor, PKD nephrologist, someone that can specifically tell them about their own journey.
Kristen Meinzer: Many great resources. Dr. Chebib, thank you so much for bringing your expertise and also your personal story to the show today. I’m so moved by what you and your family have gone through, your journey in trying to help others, and all of the optimism that you’ve brought to the conversation today. Thank you so much.
Dr. Fouad Chebib: Thank you so much for having me and for raising awareness. Again, happy to answer any questions from your audience. I’m sure they’re savvy enough to reach out to me, whether by email or LinkedIn or Twitter. I’m always happy to help out or connect with them and get their questions answered.
Kristen Meinzer: PKD treatments are constantly evolving. But right now, the main achievable goal is to slow or halt the progression of PKD through lifestyle and medication. Lifestyle includes maintaining a healthy weight, eating a healthy low-salt diet, and drinking lots of water. These habits help keep the blood pressure low and the thirst hormone from being stimulated.
There’s also a medication called Tolvaptan, which suppresses the thirst hormone. We’re already seeing the results of these treatments: people experiencing more and more years of function in the kidneys they were born with. But what’s most exciting is the future of PKD treatment. There are new gene therapies being developed to target specific PKD mutations in the DNA.
It’s hard not to share Dr. Chebib’s optimism that a cure may one day be within reach. Okay, that’s all for this episode. But if you’ve got a question or topic suggestion, you can leave us a voicemail at (507) 538-6272. We might even feature your voice on the show.
If you want to learn more about PKD, we’ll add a link to Mayo Clinic’s PKD Resource Center in the show notes.
For more “Health Matters” episodes and resources, head to mayoclinic.org/healthmatters. If you found this show helpful, please subscribe, and make sure to rate and review us on your podcast app — it really helps others find our show. Thanks for listening, and until next time, take care and stay healthy.
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